Invitation etiquette

So I had sent STDs out awhile ago and about a week ago, my FH's cousin called to say that her family can't come. (Not a problem because we want about 50 declines.) Now I'm not clear about the next part, but either my FH said ok so we won't send the invite or his cousin said don't worry about sending an invite. If he said it, I think he was thinking one less invite for me to fill out! (I'm doing all the addressing because he's got TERRIBLE handwriting). But she may have been the one to say it. I just don't know.

Anyway. The question is: if his cousin was the one to say not to send the invite, do I still send one? I don't want to annoy her by sending one. I've never even met her. But I know that if a person gets an STD, they get an invite, even if they say they can't come, because plans change. If I knew it was my FH who said it, I'd send the invite. He just says he doesn't remember.